A set of golf clubs traditionally comprises a number of woods, generally a driver or No. 1 wood, a No. 2 wood, a No. 3 wood, and a No. 4 wood, and a number of irons, generally irons No. 2 through No. 9, and a wedge. Under the prevailing rules of the Professional Golfers Association, a golfer may carry no more than fourteen clubs, which limitation allows a golfer to carry each of the basic clubs enumerated above in addition to a putter. The clubs are designed with graduated loft angles, i.e. the angle between a vertical plane intersecting the club face and the planar surface of the club face, the varying loft angles allowing a golfer to selectively vary the distance of travel of a golf ball without altering his normal full swing by merely using a club with a different loft angle. The woods are designed with relatively small loft angles, and are capable of hitting a golf ball relatively longer distances than are irons, the driver having the least loft with the Nos. 2, 3, and 4 woods having progressively greater loft angles, respectively. Similarly, the loft angle of irons progressively increases as the identifying club number increases, the wedge having the greatest loft angle of any club.
Due to the differing loft angle, the distance variation between any two golf clubs in sequence (e.g. a 7 iron and an 8 iron) is approximately ten yards under normal conditions, and, therefore a full set of clubs is generally sufficient to enable a golfer to make a shot of almost any desired distance without altering his normal swing by merely selecting the club with the appropriate loft angle. Many golfers, however, do not carry a full set of clubs but instead carry a set of clubs usually referred to as a "short set", i.e. a driver, a 3 wood, irons Nos. 3, 5, 7 and 9, and a putter. For golfers carrying a short set of clubs, the variation in distances attainable from club to club are obviously significantly greater than with a full set of clubs. Additionally, even when a golfer has a full set of clubs available, the wedge is the club having the greatest loft angle and is therefore the club capable of accurately hitting a golf ball the shortest distance when a normal swing is used, generally a maximum of approximately 115 yards. Therefore, the wedge is used in attempting many shots of a distance substantially less than 115 yards, and there is a significant distance variation over which a golfer must be capable of using the wedge accurately. A very similar problem exists for those golfers who use a set of clubs, such as a short set, in which the 9 iron is the club having the greatest loft angle.
When the golfer using a short set of clubs finds himself confronted with a shot which normally would require one of the intermediate clubs which he does not have, he has three alternatives: (1) he can use the club having the next greater loft angle and attempt to strike the ball with greater force than he normally would, this alternative being the least preferable, (2) he can use the club having the next lower loft angle and attempt the shot using less than a full swing, or (3) he can use the club having the next lower loft angle, "opening" the face of the club so that the club face assumes a greater loft angle with respect to a vertical plane therethrough, and attempting the shot with a normal swing. When a golfer finds himself a shorter distance from the hole than the distance a full wedge, or 9 iron, shot will travel, he has available the second and third alternatives just described. Regardless of the choice made, it is difficult to precisely determine either the degree to which the golfer should reduce his swinging force or the degree to which he should "open" the club face in order to execute the shot properly. Even when a golfer successfully executes a shot using either of the alternative methods above, a later shot made under similar circumstances will probably not be consistent with the successful shot since the golfer has no available reference by which he can remember the degree to which he reduced his swing or opened the club face.
The present invention provides a unique, calibrated system of marking the club face of golf clubs, the markings serving as accurate references whereby the club head of any individual club may be selectively oriented with respect to the intended line of travel of the golf ball to allow selective variation of the effective loft angle of the club and, therefore, selective variation of the distance of travel of a golf ball struck by the club head. More particularly, the present invention enables a golfer using a short set of clubs to selectively and accurately orient the club head of any individual club in his set to cause the club face to effectively assume the loft angle of the next higher numbered club in the normal numbering sequence of a full set of clubs, i.e. one of the intermediate clubs not normally included in a short set of clubs. Additionally, the present invention enables a golfer, when confronted with a shot of a lesser distance than a full wedge, or a full nine iron when a wedge is not available, to selectively and accurately open the club face of his golf club a predetermined amount, causing the club face to assume a greater loft angle and permitting the golfer to make the shot by using a normal full swing.